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The introduction of dipoles on gold nanoparticle surfaces provides the formation of chain-like nanoparticle assemblies in solution under ambient conditions. Here, we present studies on influencing and controlling the strength of the induced dipole by thiols. Aromatic thiols lead to enhanced surface dipoles, where electron-donating functions can further increase the interaction. Thereby, particle–particle distances and chemical environment at the particle interface were manipulated, which resulted in different tunneling resistances Rg in these 1D structures. Here, Rg seemed to be mostly dominated by the interparticle distance rather than the type of ligand. Temperature-dependent current–voltage measurements of thiol-bearing nanoparticle chains revealed two different transport mechanisms. For temperatures <170 K, a thermally activated electron tunneling takes place, which depends on the charging energy Ec. Whereas for higher temperatures, a transition to an electron hopping process occurs determined by the involved thiol and nanoparticle shape. For structures with strong interparticle electronic coupling, the conduction mechanism is almost temperature-independent, which makes them promising candidates for highly sensitive chemiresistor sensors. [ABSTRACT FROM AUTHOR]

Colloidal crystals are arguably one of the most promising candidates when it comes to the fabrication of nanostructured metamaterials. Especially mesocrystals show exciting new properties that emerge from their inherent directional oriented assembly. With this work, the electrical conductivity of well‐defined micrometer‐sized platinum nanocube‐based mesocrystals is demonstrated and tuned through the variation of different capping agents. Herein, a method is presented to reproducibly quantify the intrinsic resistance of individual mesocrystals through electrical nanoprobing and focused ion beam deposition contacting. A thermally activated tunneling mechanism is identified as the main effect for electron propagation. In addition, the mesocrystals are altered through organically linking and mineral bridging the individual nanoparticles. This results in an increase in mesocrystal rigidity and, more importantly, conductivity by seven orders of magnitude while retaining shape, structure, and composition. In addition, these observations are transferred onto multicomponent superstructures in the form of binary mesocrystals. There, it is demonstrated that the electrical properties could be tuned through the ratio of nanoparticles incorporated into a mesocrystalline host system while simultaneously maintaining potential catalytic or superparamagnetic features of the guest particles. [ABSTRACT FROM AUTHOR]

Binary mesocrystals offer the combination of nanocrystal properties in an ordered superstructure. Here, we demonstrate the simultaneous self‐assembly of platinum and iron oxide nanocubes into micrometer‐sized 3D mesocrystals using the gas‐phase diffusion technique. By the addition of minor amounts of a secondary particle type tailored to nearly identical size, shape and surface chemistry, we were able to promote a random incorporation of foreign particles into a self‐assembling host lattice. The random distribution of the binary particle types on the surface and within its bulk has been visualized using advanced transmission and scanning electron microscopy techniques. The 20–40 μm sized binary mesocrystals have been further characterized through wide and small angle scattering techniques to reveal a long‐range ordering on the atomic scale throughout the crystal while showing clear evidence that the material consists of individual building blocks. Through careful adjustments of the crystallization parameters, we could further obtain a reverse superstructure, where incorporated particles and host lattice switch roles. [ABSTRACT FROM AUTHOR]

Abstract: Biogenic nucleation and crystallization occur in confined spaces with defined interfacial properties. However, the regulatory functions of organic players in the stabilization and transport of inorganic precursors such as ion clusters, liquid‐condensed phases, and amorphous particles are unclear. Given the prevalence of unstructured proteins in biogenic materials, the present study investigates the effects of biomineral‐associated, intrinsically disordered protein domains with simple and repetitive amino acid compositions on mineral nucleation and their capability to form distinct supramolecular assemblies. The quantitative assessment and structural evaluation of the nucleation process reveal that disordered regions confine hydrated mineral precursors within vesicles, transiently suppressing mineral precipitation. Stabilization of the amorphous mineral is attributed to protein self‐association and restructuration toward β‐configurations, triggered by specific bioinorganic interactions. In consequence, the conditioned macromolecules localize at phase boundaries formed upon liquid–liquid demixing of mineral precursors and stabilize the fluidic mineral precursors against crystallization. Thus, the conformational plasticity and self‐association of intrinsically disordered sequences in response to crystallization environments mediates the selection of functional macromolecular subensembles dedicated to biomaterial growth. [ABSTRACT FROM AUTHOR]

The self-assembly of alkaline earth carbonates in the presence of silica at high pH leads to a unique class of composite materials displaying a broad variety of self-assembled superstructures with complex morphologies. A detailed understanding of the formation process of these purely inorganic architectures is crucial for their implications in the context of primitive life detection as well as for their use in the synthesis of advanced biomimetic materials. Recently, great efforts have been made to gain insight into the molecular mechanisms driving self-assembly in these systems, resulting in a consistent model for morphogenesis at ambient conditions. In the present work, we build on this knowledge and investigate the influence of temperature, supersaturation, and an added multivalent cation as parameters by which the shape of the forming superstructures can be controlled. In particular, we focus on trumpet- and coral-like structures which quantitatively replace the well-characterised sheets and worm-like braids at elevated temperature and in the presence of additional ions, respectively. The observed morphological changes are discussed in light of the recently proposed formation mechanism with the aim to ultimately understand and control the major physicochemical factors governing the self-assembly process. [ABSTRACT FROM AUTHOR]

In this review, we briefly summarize the history of mesocrystal research. We introduce the current structural definition of mesocrystals and discuss the appropriate base for the classification of mesocrystals and their relations with other classes of solid state materials in terms of their structure. Building up on this, we comment on the problems in mesocrystal research both fundamental and methodological. Additionally, we make the short overview of the mesocrystal formation principles and synthetic routes used for their fabrications. As an outlook into the future, we highlight the most notable trends in mesocrystal research and developments. [ABSTRACT FROM AUTHOR]

Despite numerous studies on the nucleation and crystallization of iron (oxyhydr)oxides, the roles of species developing during the early stages, especially primary clusters and intermediate amorphous particles, are still poorly understood. Herein, both ligand-free and ligand-protected amorphous iron oxide (AIO) clusters (<2 nm) were synthesized as precursors for magnetite formation. Thermal annealing can crystallize the clusters into magnetite particles, and AIO bulk phases with domains of pre-aligned clusters are found to be direct precursors to crystals, suggesting a non-classical aggregation-based pathway that differs from the reported oriented attachment or particle accretion mechanisms. [ABSTRACT FROM AUTHOR]

The supreme aim of nanoparticle-based materials is to achieve new properties extending over the features of individual constituents. The emergence of cooperativity necessitates precise positioning and orientation of nanoparticle ensembles. Thus, it is important to understand and learn how to control self-assembly processes of nanoparticles. Besides shape, the structural uniformity plays a key role for ordering in superstructures. Therefore, it is challenging to synthesize nanorods with narrow polydispersity. An analysis of the systematic variation of aspect ratio and polydispersity is missing. A series of zinc oxide nanorods is presented and it is shown that their formation resembles step-polymerization with an amorphous precursor state as a monomer and polar ZnO particles as entities capable of growing. The width of nanorods is kept constant (15 nm) and the length is varied between 20 and 100 nm, as well as improving the polydispersity of the nanorod length from 36% to 10%. Best samples have been achieved by post-preparative treatment using gradient centrifugation. A method has been developed for semiquantitative evaluation of orientational order. Ordering in structures formed by quasispherical particles is always low despite low polydispersity. For rod-like nanoparticles with increasing aspect ratio, superstructure order depends on the occurrence of different defects, which correlate differently to nanoparticle polydispersity. [ABSTRACT FROM AUTHOR]

Biomineralization can afford crystal frameworks of great diversity and utmost complexity, frequently featuring hierarchical structures and morphologies beyond any crystallographic restrictions. The formation of such architectures is usually directed by organic molecules or matrices, which modify crystallization in a deliberate manner. Their influence often leads to sinuous forms, which, by intuition, suggest the presence of life and distinguish these minerals from their inanimate, mostly euhedral counterparts. However, such a strict distinction does not hold. In fact, smooth curvature and higher-order structuring can occur also in purely inorganic environments: simply by precipitating alkaline earth carbonates in silica-containing media, aggregates of highly oriented carbonate nanocrystals can be obtained that display striking noncrystallographic morphologies such as regular helicoids. Thereby, individual crystallites as well as the entire assembly are sheathed by amorphous silica, thus giving a composite material with various levels of hierarchy. These exceptional forms, called 'silica biomorphs', self-assemble through a bottom-up process, which relies on local variations in the conditions and is driven by a pH-based coupling of the carbonate and silicate. Here, we review recent progress in the field of silica biomorphs with particular focus on their mechanism of formation, provide insight into structural details at different length scales, and discuss implications of these biomimetic crystal aggregates for both primitive life detection and materials science. [ABSTRACT FROM AUTHOR]

Anisotropy, mesocrystal, nanoparticle, self-assembly, superlattice Keywords: anisotropy; mesocrystal; nanoparticle; self-assembly; superlattice EN anisotropy mesocrystal nanoparticle self-assembly superlattice 1 1 1 01/06/22 20220110 NES 220110 B Binary mesocrystals b demonstrate the combination of nanocrystals from different materials within a highly ordered manner. Cover Picture: 3D Binary Mesocrystals from Anisotropic Nanoparticles (Angew. [Extracted from the article]

Platinum nanoparticles are widely known for their numerous electrochemical and catalytic applications. Enhanced or novel properties that may arise when ordering such particles in a highly defined manner, however, are still subject to ongoing research, as superstructure formation on the mesoscale is still a major challenge to be overcome. In this work, we therefore established a reproducible method to fabricate micrometer-sized superstructures from platinum nanocubes. Through small-angle X-ray scattering and electron diffraction methods we demonstrate that the obtained superstructures have a high degree of ordering up to the atomic scale and, therefore, fulfill all criteria of a mesocrystal. By changing the solvent and stabilizer in which the platinum nanocubes were dispersed, we were able to control the resulting crystal habit of the mesocrystals. Aside from mesocrystal fabrication, this method can be further utilized to purify nanoparticle dispersions by recrystallization with respect to narrowing down the particle size distribution and removing contaminations. [ABSTRACT FROM AUTHOR]

The solubilization of targeted compounds represents key criteria in the sophisticated field of medical chemistry but also in technical applications like scale removal. Especially, the simultaneous dissolution of two chemically different compounds remains challenging. Herein, macromolecular solubilizers are introduced for the simultaneous dissolution and encapsulation of poorly water‐soluble cholesterol and hydroxyapatite. The peptide‐based, amphiphilic block copolymers possess physicochemically disparate segments combined in one polymer chain as binding sites for hydrophobic as well as ionic materials. Small polymer libraries are synthesized and screened for structure–property relationships. Complementary analytical techniques suggest polymeric self‐assembly into spherical adaptive nanoparticles with the fundamental ability to passively absorb significant amounts of hydrophobic cholesterol up to 33 wt%. Furthermore, the additional incorporation of acidic domains enables the simultaneous dissolution of hydrophobic compounds and mineral phases such as hydroxyapatite. Ultimately, those nontoxic block copolymers can be used to solubilize and absorb other lipophilic and ionic compounds such as Sudan III dye and calcium ions. Such multifunctional nanomaterials have a wide range of direct application for simultaneous dissolution or delivery of hydrophobic molecules and cations resp. minerals for instance in the field of atherosclerosis. [ABSTRACT FROM AUTHOR]

Learning which parameters influence order is important for the generation of future particle‐based materials. Aspect ratio and polydispersity could be influenced independently from each other for ZnO nanorods. Sebastian Polarz and co‐workers deduce the impact on order parameters and structural defects from a quantitative evaluation of electron microscopy data in article number 1600215. [ABSTRACT FROM AUTHOR]